( function () {
const _v1 = new THREE.Vector3();

const _v2 = new THREE.Vector3();

const _normalMatrix = new THREE.Matrix3();

class VertexNormalsHelper extends THREE.LineSegments {
  constructor(object, size = 1, color = 0xff0000) {
    let nNormals = 0;
    const objGeometry = object.geometry;

    if (objGeometry && objGeometry.isGeometry) {
      console.error('THREE.VertexNormalsHelper no longer supports Geometry. Use THREE.BufferGeometry instead.');
      return;
    } else if (objGeometry && objGeometry.isBufferGeometry) {
      nNormals = objGeometry.attributes.normal.count;
    } //


    const geometry = new THREE.BufferGeometry();
    const positions = new THREE.Float32BufferAttribute(nNormals * 2 * 3, 3);
    geometry.setAttribute('position', positions);
    super(geometry, new THREE.LineBasicMaterial({
      color,
      toneMapped: false
    }));
    this.object = object;
    this.size = size;
    this.type = 'VertexNormalsHelper'; //

    this.matrixAutoUpdate = false;
    this.update();
  }

  update() {
    this.object.updateMatrixWorld(true);

    _normalMatrix.getNormalMatrix(this.object.matrixWorld);

    const matrixWorld = this.object.matrixWorld;
    const position = this.geometry.attributes.position; //

    const objGeometry = this.object.geometry;

    if (objGeometry && objGeometry.isGeometry) {
      console.error('THREE.VertexNormalsHelper no longer supports Geometry. Use THREE.BufferGeometry instead.');
      return;
    } else if (objGeometry && objGeometry.isBufferGeometry) {
      const objPos = objGeometry.attributes.position;
      const objNorm = objGeometry.attributes.normal;
      let idx = 0; // for simplicity, ignore index and drawcalls, and render every normal

      for (let j = 0, jl = objPos.count; j < jl; j++) {
        _v1.set(objPos.getX(j), objPos.getY(j), objPos.getZ(j)).applyMatrix4(matrixWorld);

        _v2.set(objNorm.getX(j), objNorm.getY(j), objNorm.getZ(j));

        _v2.applyMatrix3(_normalMatrix).normalize().multiplyScalar(this.size).add(_v1);

        position.setXYZ(idx, _v1.x, _v1.y, _v1.z);
        idx = idx + 1;
        position.setXYZ(idx, _v2.x, _v2.y, _v2.z);
        idx = idx + 1;
      }
    }

    position.needsUpdate = true;
  }

}

THREE.VertexNormalsHelper = VertexNormalsHelper;
} )();
